Refuse collection vehicles with which the present invention is concerned are of the type that include a wheel-supported vehicle chassis, a refuse container body mounted on the vehicle chassis and having an open end, and a tailgate mounted to the body so as to close the open end. Typically, the open end is the rear end of the refuse container body. The tailgate has an upper edge that is pivotally mounted to the top of the container body and can be swung upwardly to uncover the open rear end to allow refuse to be discharged from the container body. Alternatively, the tailgate can be part of a removable container that is capable of being removably mounted on the vehicle chassis, typically using rollers and guide rails.
Locking mechanisms for securing the tailgate in a closed position against the rear end of the body are known in the art. One type of locking mechanism comprises a screw threaded member pivotally mounted on each side of the container body and manually rotated into position with an apertured bracket positioned on each side of the tailgate. This arrangement has the disadvantage of requiring the vehicle operator to manually lock or unlock first one side of the tailgate and then walk around to the other side to perform the locking/unlocking procedure, resulting in a time-consuming and cumbersome procedure.
Another type of locking mechanism is disclosed in U.S. Pat. No. 3,873,149, wherein power actuated rams release the tailgate from the container body and pivot the tailgate first into a raised open position and then down into a locked closed position. Another power actuated locking mechanism is disclosed in British Patent No. GB 2093902, wherein a piston and cylinder assembly acts on a spring loaded plunger to withdraw the plunger from a bracket on the container body to unlock the tailgate.
Although these mechanisms have the advantage of allowing the operator to perform the locking/unlocking procedure from one side of the vehicle by using power controls, the operator must still walk around to the other side of the vehicle to visually check the remote locking cylinder to confirm that the locking cylinder is either in the locked or unlocked position.
One solution to overcome the visual inspection drawback has been to employ multiple sensors to detect the different positions of all the locking cylinders. Such sensors, however, can be subject to mechanical or electrical failure, and increase the cost of the vehicle.
It is, accordingly, an object of the present invention to provide a tailgate locking mechanism that does not require visual inspection of a remote or hidden locking cylinder to determine the locking position.
Another object of the invention is to provide a hydraulic locking mechanism that does not rely upon electrical position sensors.
A further object of the invention is to provide a hydraulic circuit tailgate locking mechanism that operates in series such that the locking position of a second hydraulic latch, which is on the side of the vehicle opposite and not visible to the operator, is known from the locking position of a first latch visible to the operator.
A still further object of the invention is to provide a locking mechanism that is simple, reliable, and cost effective.